uniq: Flush BufWriter, make error context GNU-like

src/uu/uniq/src/uniq.rs

@@ -110,6 +110,7 @@ impl Uniq {
         {
             write_line_terminator!(writer, line_terminator)?;
         }
+        writer.flush().map_err_context(|| "write error".into())?;
         Ok(())
     }
 
@@ -226,7 +227,7 @@ impl Uniq {
         } else {
             writer.write_all(line)
         }
-        .map_err_context(|| "Failed to write line".to_string())?;
+        .map_err_context(|| "write error".to_string())?;
 
         write_line_terminator!(writer, line_terminator)
     }

tests/by-util/test_uniq.rs

@@ -1181,3 +1181,14 @@ fn test_stdin_w1_multibyte() {
         .succeeds()
         .stdout_is("à\ná\n");
 }
+
+#[cfg(target_os = "linux")]
+#[test]
+fn test_failed_write_is_reported() {
+    new_ucmd!()
+        .pipe_in("hello")
+        .args(&["-z"])
+        .set_stdout(std::fs::File::create("/dev/full").unwrap())
+        .fails()
+        .stderr_is("uniq: write error: No space left on device\n");
+}